The present invention relates to a rod cradle for a film, coating, or dam rod, which rod cradle includes a frame profile equipped with an insert groove, an insert fitted to this equipped with a rod groove and a rod, and locking elements for locking the insert into the frame profile, and on the sides of the insert groove in the frame profile there are edges and on the sides of the rod groove there are opposing lips corresponding to them, and the lips include a vertex, a cover surface, which cover surface is in contact with the rod when the rod is in the rod groove, and a vertex surface, which separates from the cover surface at the vertex. The invention also relates to a corresponding insert and a method.
Rod cradles are used mainly in sizing and coating devices operating on the film-transfer principle and in coating application taking place directly onto the surface of the paper. A rod cradle, in which there is a separate insert, is, as such, known. In such rod cradles, the locking of the insert is implemented by means of a locking hose, as disclosed in publication WO3078077. A rod cradle with an insert is a good solution, as rod cradles must be changed regularly, which leads to spare-parts costs. When the component to be changed is only the wearing part, i.e. the insert, instead of the rod cradle, both cost savings and a reduction in waste material are achieved in device servicing.
When locking the insert using a locking hose, the locking hose must be located in the rod cradle, which is not, however, technically reliable. A drawback when using the locking-hose technique is the uncertainty of the locking, if pressure is lost for some reason, for example, if the hoses leak, or are wrongly connected. In addition, the implementation of the hose locking leads to costs, as a separate groove for the hose must be cast or machined. In addition, the additional grooves in the frame of the rod cradle may cause excessive flexibility in the frame of the rod cradle. The use of a locking hose is also significant in terms of work safety, as, if the locking hose fractures, the force retaining the insert disappears and the rod or the insert can detach, causing a dangerous situation.
The locking of the rod can also be based on using loading means to press the rod cradle towards the surface, on which, for example, coating is being applied. In this embodiment too, the problem is the uncertainty of whether the rod and the insert will remain in the groove, for example, if the loading is momentarily reduced. In addition, problems can arise when application is starting, when the loading means may not yet be pressing towards the application surface with sufficient force to hold the rod in its groove in the rod cradle.
FIG. 1 shows one rod cradle according to the prior art. The rod cradle includes a frame profile 12 equipped with an insert groove 14. An insert 16, equipped with an rod groove 18, and a rod 28 and locking elements 24 are fitted to the frame profile 12. The locking of the insert 16 to the frame profile 12 takes place with the aid of these locking elements 24. At the sides of the insert groove 14 in the frame profile 12, there are edges 20. On the sides of the rod groove 18 there are lips 22 corresponding to them. The lips 22 include a cover surface 72, 72′, which is in contact with the rod 28, when the rod 28 is in the rod groove 18, as well as a vertex surface 70, 70′, which starts from the cover surface 72 at its extreme vertex of contact with the rod, i.e. at the vertex 74, 74′. In the solution according to the prior art, the rod is first placed in the insert, which is then placed in the frame profile. The locking that takes place using the locking elements can be ensured, for example, using the locking hose described above.